Inking pad



June 6, 1950 SHERMAN 2,510,838

INKING PAD Filed July 17, 1947 J JEQZ A TTOR/VE VS Patented June 6, 1950 I I a 1' UNITED STATES PATENT OFFICE INKING PAD Herbert P. Sherman, Chicago, Ill.

1 '1 Application July 17, 1947, Serial No. 761,660

11 Claims. (Cl. 101-119) This invention relates to an inking pad which is especially useful on duplicating machines.

In duplicating machines ink is fed through a perforated member such as a drum to a stencil and through the stencil to a sheet to be printed. Between the stencil and the perforated drum, it is necessary to provide an inking pad. This pad is made of absorbent material or cloth and forms a compressible ink distributing means which absorbs ink from the spaced holes in the drum and distributes it evenly to the under surface of the stencil. In the printing process a sheet of paper is rolled or pressed against the stencil. For example, a pressure roller (usually with a relatively soft rubber surface) having its axisparallel to the drum is provided and the sheet to be printed is passed between the drum and the pressure roller. As the pressure roller and th drum rotate ink is pressed ahead of the pressure roller and when the pressure roller reaches the end of the stencil a considerable pool of ink has accumulated. This pool sometimes causes more ink to be forced out of the stencil at the end of the stencil, it always causes undesirable ink leakage and seepage at the end and sides of the drum and it causes undesirable pressure on the stencil as the pressure roller must eventually pass over'the ac-. cumulated pool of ink. The orifices of the drum permit some of the ink to return to the inside of the drum but for high speed operation the ink does not return as easily as is desirable to secure the best results.

An object of this invention is to provide an inking pad for a duplicating machine which avoids the formation of an' ink pool at the end of the stencil. Another object of the invention i to provide an inking pad for a stencil printing machine which prevents seepage and leakage of ink at the sides and end of the stencil. Another object of the invention is to provide an inking pad in combination with a perforated stencil which combination avoids the formation of an ink pool between the end of the stencil and obtained by making an inking pad having, its edges and ends impregnated with a pore closing, ink-repelling and/ or a non-absorbent inert coating material and by forming the pad with a transverse row of relativel large holes located adjacent that end which is passed over the pressure roll last. The transverse row of holes is located adjacent the boundary of the impregnated and non-impregnated end portion of the pad and the pad is so proportioned in length relative to the drum or other stencil support to which it is to be applied that the row of openings or holes in the pad precedes at least the last row of openings in the drum or other stencil support.

The pad is made of absorbent fabric material. It may be made of cotton, wool, ramie, paper, ink absorbent rayons such as regenerated cellulose type of rayons or mixtures of these fibers. The fabric of which the pad is composed may be woven, felted or knitted.

The edge and end portions of the pad may be impregnated with any desired pore closing material. The pore closing material may be applied to the pad in the formv of a solution, for exampl in the form of a paint, a varnish or 'a lacquer. Suitable pore closing solutions may include solutions of plastic cellulose derivatives such as $0111? tions of cellulose nitrate, cellulose acetate, cellulose butyrate, ethyl cellulose, ethoxy cellulose, cellulose acetate-propionate, etc. Other plastic coating compositions such as those made from polymeric vinyl compounds, phenol-formaldehyde resins, polyamides, shellac, natural resins, alkyd resins and drying oils may b employed. The coating material must be inert to th ink which is to be employed. The impregnant may be colored for the sake of its appearance or for the purpose of indicating its size or its ink resistance.

Any solvent may be employed to dissolve the plastic coating material andto serv as the vehicle for applying the coating material to the pad. Most varnish, lacquer, paints and coating compositions commercially sold are capable of coating fabrics and are inert to ink and are therefore suitable. An example of a typical coating composition is a 25% solution of a copolymer of vinyl chloride and vinyl acetate in toluene,

The novel features that I consideroharacteristic of my invention are set forth withparticularity in the appended claims. Th invention, itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will'best' be understood from the following description of a specific placed on the lugs.

embodiment when read in connection with the accompanying drawing, in which Figure 1 is a plan view of the pad of the pres ent invention.

Figure 2 is a perspective View showing the pad and a stencil being applied to a drum of a duplicating machine.

Figure 3 is a perspective view, partly broken away showing the pad and stencil in place on a drum of a duplicating machine.

Figure 4 is a partial plan view of a modified form of pad.

In the drawings, the pad I is shown as having a center ink absorbent portion ll, two side portions l2 and I3 which are nonabsorbent for ink, and the end portions I l and 55 which are also non-pourous or non-absorbent to ink. Thus the ink is held within the area ii. If desired the impregnated side portions l2 and 13 may be omitted. The end I4 is provided with a plurality of orifices 2.0, 21 and 22 which serve to hold the end of the pad to the drum. The impregnated portion 14 preferably, completely surrounds these openings 20, 21 and 22 because it furnishes additional reinforcement for the openings and prevents unraveling, etc.

The impregnated end l is shown as ending in a trapezoidal portion 23. This trapezoidal end portion has some advantage in attaching the end of the pad to the drum but is entirely optionaL One of the essential features of the invention is the provision of the holes or orifices 3l-3 8 at the line where the absorbent portion i l joins the end impregnated portion i5. The number of these orifices is optional, even a few of such orifices improves the performance of the device.

The way in which the pad is applied to a duplicating machine is illustrated somewhat diagramatically in Figures 2 and 3 The parts of the duplicating machine shown include a drum 4!] which has a curved outer surface 4| in the form of a portion of a cylinder, with sides or ends 42 and 43 to close the ends of the cylinder. Suitably attached to one side 62 is a crank 46 for rotating the drum. Other means may be pro- 1 vided for rotating the drum. The drum is contacted from below by a pressure roller M which preferably has a soft rubber surface. A suitable support for paper which is to be discharged from between the printing rolls 4E and id, is shown at 4.5.

On the inside of the cylinder, lugs 5B, 5% and 52 are provided on which the end it or th pad l0 and a stencil 53 are adapted to be hung. The holes 2D, 21 and 22 in the pad and .a corresponding set of holes in the stencil are spaced to fit the lugs 50, 5| and 52. To provide against accidental unhooking of the pad or stencil, a pivoted U-shaped rod 55 is provided to press against the ends of the stencil and pad after the said ends are This method of attaching the stencil and pad is for purposes of illustration only and does not form a part of the present invention.

After the pad and stencil have been attached at one end to the drum 4!! the pad and stencil is then wrapped around the drum and attached at the other inside portion of the drum by a U-shaped clamping rod 51 which is shown in non-clamping position in Figure 2 and in clamping position in Figure 3. If desired the end of the stencil 53 may also be of trapezoidal shape to aid in threading it between the drum and the clamping rod 51. The peripheral surface of the drum is perforated as shown at 53. These perforations permit the ink which is fed from the inside of the drum to pass through the drum to the absorbent portion ll of the pad The pad absorbs the ink and uniformly distributes it over the rear surface of the stencil 53. The ink, of course, then passes through the openings in the stencil to a surface to be printed such as the surface of a paper sheet 6| shown passing through the machine in Figure 3.

In order to operate to the best advantage the length of the absorbent area ll of the pad [0 is coordinated with the length of the stencil support so that the large row of openings 3 I-38 lies adjacent to but spaced ahead of at least the last row orifices 60 of the stencil support. As shown in Figures 2 and 3 the drum 40 is rotated in a clockwise direction and the sheet to be printed is fed from the right to the left. As the drum is rotated in a clockwise direction a pool of ink begins to build up to the right of the point where the drum 4D and the roller 44 press against each other. If no provision is made for the escape of this pool of liquid it may seep out the sides or cause undesirable pressure against the stencil especiallyat that area of the drum which lies in a counterclockwise direction to the last row of orifices of the drum. The pad of this invention provides for release of this pool of ink and for the return of the ink to the feeding side of the drum before the pool reaches the end of the stencil or drum.

The holes 3i38 in the pad it! provide extra space into Which the pool of .ink can flow and they also provide a substantially unobstructed passage to the inside of the drum (through the last one or two rows of orifices 56.). Since the end portion of the ink pad beyond the row of orifices 3l38 is impregnated with ink repelling materials no further pool of ink is formed and in fact the small amount of ink which may pass beyond the row of orifices is squeezed back through the last row of orifices 60 or back into, the space formed by the orifices 34-438 of the pad.

The impregnation of the ends and sides of the pad also increases the thickness and decreases the softness of the pad in the impregnated areas so that the impregnated border forms a narrow rim about the surface of the stencil or stencil support to positively trap the ink in the desired ink-transfer area.

'In the modified form of pad shown in Figure 4 not only the end 15 (not shown) contains openings where the impregnated area meets the absorbent area but the sides and/or the end it also contain openings. Openings ll, l2, l3, and 14 are shown at side 13 openings l5, 25, ll and 78 are shown at side [2 and openings 19, 81 and 8! are shown at the line where impregnated end l4 meets the absorbent area ll. Thus the openings relieve the pressure which results from the formation of even small pools of ink at the sides l2, l3 and end [4 of the inking pad.

It is apparent that this invention effectively overcomes some of the most disturbing disadvantages which are present in the stencil type of duplicating machines. The disadvantages which are overcome include thespoilage due to seepage of ink, the loss of ink due to leakage, the distortion of stencils due to the presence of a trapped pool of liquid ink, etc.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. A fibrous inking pad having ends for attaching the pad to a stencil duplicating machine, at least one end of said pad being ink repelling, an area of the pad intermediate the ends being ink absorbing, a plurality of enlarged holes in said pad adjacent the boundary line between an ink repelling end portion and the ink absorbing portion of said pad.

2. A fibrous inking pad having ends for attaching the pad to a stencil duplicating machine, both ends of said pad being ink repelling, an area of the pad intermediate the ends being ink absorbing, a plurality of enlarged holes in said pad adjacent the boundary line between an ink repelling end portion and the ink absorbing portion of said pad.

3. A fibrous inking pad having ends for attaching the pad to a stencil duplicating machine, the ends and the sides of said pad being ink repelling and the central area thereof being ink absorbent, a plurality of enlarged holes in said pad adjacent the boundary line between :an ink repelling end portion and the ink absorbing portion of said pad.

4. A fibrous inking pad having ends for attaching the pad to a stencil duplicating machine, said pad having a plastic coating at the ends thereof to make the coated portion ink repelling, an area of the pad intermediate the ends being ink absorbing, a plurality of enlarged holes in said pad adjacent the boundary line between an ink repelling end portion and the ink absorbing portion of said pad.

5. In a stencil duplicating machine, a curved stencil supporting means having a porous area adapted to supply ink from the porous area thereof to ink the stencil, in combination with a fibrous inking pad adapted to be held at its ends between the porous support and the stencil to spread the ink over the stencil, said fibrous inking pad having an ink absorbing area of substantially the same width but of slightly smaller length than the porous area of said supporting surface, said fibrous pad also having an ink-repelling area contiguous with said ink-absorbing area at at least one end thereof, said pad having a plurality of relatively large holes in a portion of the ink-repelling area adjacent the ink-absorbing area, said holes in said pad coinciding with some of the holes at the end of th porous area of the supporting surface.

6. In a stencil duplicating machine, a curved stencil supporting means having a porous area adapted to supply ink from the porous area thereof to ink the stencil, in combination with a fibrous inking pad adapted to be held at its ends between the porous support and the stencil to spread the ink over the stencil, said fibrous V inking pad comprising a single sheet of fibrous material having an ink absorbing area and an ink repelling area, the ink absorbing area substantially coinciding with the porous area of said stencil support except that it is slightly shorter than said porous area on one end, said ink repelling area being impregnated with a plastic material to increase its bulk, and to make it nonporous and ink-repellant, said ink repelling area including at least one of the end portions of said pad and a plurality of relatively large holes at a line Where the ink-repelling area at the end portion joins the ink-absorbing area.

7. In a stencil duplicating machine, a curved stencil supporting means having a porous area adapted to supply ink from the porous area thereof to ink the stencil, in combination with a fibrous inking pad adapted to be held at its ends between the porous support and the stencil to spread the ink over the stencil, said fibrous inking pad having an ink absorbing area of substantially the same width but of slightly smaller length than the porous area of said supporting surface, said fibrous pad also having a plastic impregnated ink-repelling area contiguous with said ink-absorbing area, said ink repelling area including at least one of the end portions of said pad. a plurality of relatively large holes in the end portion of the ink-repelling area adjacent the ink-absorbing area, said holes in said pad coinciding with some of the holes at the end of the porous area of the supporting surface.

8. In a stencil duplicating machine, a curved stencil supporting means having a porous area adapted to supply ink from the porous area thereof to ink the stencil, in combination with a fibrous inking pad adapted to be held at its ends between the porous support and the stencil to spread the ink over the stencil, said fibrous inking pad comprising a single sheet of fibrous material having an ink absorbing area and an ink repelling area, the ink absorbing area substantially coinciding with the porous area of said stencil supportexcept that it is slightly shorter than said porous area on one end, said ink repelling area including at least one of the end portions of said pad and a plurality of relatively large holes at a, line Where the ink-repelling area at the end portion joins the ink absorbing area.

9. The combination of claim 5 in which the ink-repelling area of the pad extends entirely around the ink absorbing area thereof thus fencing in a definite portion of the porous surface of said stencil support.

10. The combination of claim 8 in which the ink-repelling area of the pad extends entirely around the ink absorbing area thereof thus fencing in a definite portion of the porous surface of said stencil support.

11. The combination of claim 5 in which the ink-repelling area of the pad extends entirely around the ink absorbing area thereof thus fencing in a definite portion of the porous surface of said stencil support, the said ink repelling area outlining a rectangularly shaped ink absorbing area, and the said plurality of large holes a jacent the ink repelling border and the ink absorbing area being distributed over a plurality of sides of the rectangularly-shaped ink absorbing area.

HERBERT P. SHERMAN.

nnrnnnncns crrrzn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 641,495 Burnell Jan. 16, 1900 2,166,907 Herterich July 18, 1939 

